Currently, anti-rust materials commonly used in the metal processing industry are mainly divided into the following categories:
(1) Inorganic ones, mainly include sodium nitrite, molybdate, borate, etc. Among them, nitrite and molybdate are oxidative antioxidants. Rust agent, but the anti-rust film layer formed is not very dense and requires the assistance of some film-forming agents.
(2) Organic, mainly including alcohol amines, carboxylates (mainly monobasic acids, dibasic acids and tribasic acids), boric acid esters , amide, etc., this type of anti-rust materials will be used in different industries. Among them, carboxylic acids are the most widely used type of anti-rust additives. They need to be neutralized with different types of alcohol amines to form carboxylic acid amines before use. However, the cost of this type of anti-rust additives is relatively high. Borate ester rust inhibitors not only have good anti-overprinting effects, but also have certain antibacterial capabilities. However, this type of rust inhibitor is not stable enough and has the possibility of hydrolysis.
(3) Film-forming additives. At present, polyethylene glycol, sodium polyacrylate, water-soluble resin, etc. are reported more frequently. Some people have done experiments to verify them. , PEG1500 has better film-forming effect than PEG400.
Patent status of research on low-residue water-based rust inhibitors
According to the application practice of water-based rust inhibitors, the metal processing industry has increasingly higher requirements for the surface of workpieces after processing. Whether water-based rust inhibitors are used alone or When added to other water-based metalworking fluids, it is required that there should be no visible residues (including white residues, solid particles, soft sticky residues, etc.) on the surface of the workpiece after use, and it must not affect subsequent processing, such as assembly, welding, etc. Therefore, research on low-residue water-based rust inhibitors has become one of the research objects of practitioners in many industries. The research results or research progress that have been disclosed, reviewed or authorized are detailed in Table 1 below.
The characteristic of low-residue water-based rust inhibitors is that they mainly use organic substances as the main rust inhibitors, such as carboxylates, alcoholamines, boric acid, borate esters, silanes, etc. , while adding some film-forming additives to enhance the film-forming effect, such as sodium polyacrylate and polyethylene glycol. Considering the wettability and permeability, the film-forming additives can also be some surfactants or alcohol ether solvents, which can be selected The surface activities are mainly cationic surfactants and nonionic surfactants. Among them, after the cationic surfactant is adsorbed on the metal surface, the alkyl chain has a certain hydrophobic effect when exposed to the air, which helps to isolate humid air and maintain the self-cleaning function. It will be an important research direction for water-based metal rust inhibitors. .
Application status of water-based rust inhibitors
Common rust problems in the heat treatment industry are rust after tempering, rust during placement after tempering, or rust after tempering and shot blasting. In extreme cases Rust will appear after quenching and cleaning. At present, more and more customers in the industry are beginning to use environmentally friendly water-based anti-rust agents. After quenching, they are cleaned with water-based cleaning agents and rinsed with water-based anti-rust agents. However, this type of anti-rust agents has a disadvantage, because the effective anti-rust ingredients are mainly Organic matter will produce a certain amount of high-temperature decomposition after high-temperature tempering, reducing the anti-rust effect, but has little effect on low-temperature tempering. Some companies still use traditional inorganic anti-rust agents, with sodium nitrite as the main anti-rust ingredient. This type of anti-rust agent has outstanding anti-rust effects, but it is easy to crystallize on the surface of the workpiece and even absorb moisture, affecting the workpiece surface. Exterior. Some customers also use emulsified rust inhibitors, which have better resistance to moisture and heat and certain salt spray resistance.
In the process of machining metal workpieces, water-based anti-rust agents are mainly used for inter-process rust prevention, while rust-proof oil is used for storage anti-rust and long-term anti-rust. Lord. Compared with anti-rust oil, water-based anti-rust agents have better cleanability, especially for anti-rust between metal processing processes. They can be easily removed before entering the next process, or can be processed directly. At the same time, water-based anti-rust agents Agents generally have good compatibility with other water-based processing media such as cutting fluids, grinding fluids, cleaning agents, etc.
At present, this type of anti-rust agent mainly uses carboxylic acids and amines as the main anti-rust ingredients, and is combined with amides, borates, surfactants, and other ingredients. Membrane additives are compounded to achieve a synergistic anti-rust effect. If multiple materials are used to prevent rust, some non-ferrous metal corrosion inhibitors need to be added. Affected by factors such as enterprise size and business scope, geographical location, local regulations and requirements, each enterprise has different selection criteria for water-based anti-rust materials. Generally speaking, as more enterprises gradually increase their awareness of environmental protection and health, they will give priority to Choose to use green and environmentally friendly water-based rust inhibitors. However, there are still some companies that use rust inhibitor components with potential health hazards, mainly based on cost considerations, and partly to meet the company’s own expectations for rust prevention time.
In order to enhance the anti-rust performance of water-soluble industrial media products, water-based anti-rust agents can also be added to other water-based products to enhance anti-rust capabilities. In order to reduce the risk of use and experience better services, companies that use water-based rust inhibitors generally choose the same media supplier for the upper and lower processes. On the one hand, it is because the compatibility between media is better, and on the other hand, it can obtain the overall solution.
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